Method for preparing detergent compositions



May 1 1963 R. H. CHAFFEE ET AL 3,089,197

METHOD FOR PREPARING DETERGENT COMPOSITIONS Filed July 25. 1960 IN VEN TORS. Poaaer Cl/AFFEE,

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ATTORN EYE.

Unite rates tet dice 3 ,989,197 Patented May 14, 1963 3,089,197 METHOD FOR PREEARING DETERGENT COMPDSITlONS Robert H. Chalice, Cincinnati, and Richard S. Bowies,

Wyoming, @hio, assignors to The Procter & Gamble Company, Cincinnati, Ohio, a corporation of Ohio Filed July 25, 1960, Ser. No. 45,198 5 Claims. (Ci. 18-55) This invention relates to a method for use in the preparation of aerated detergent bars characterized by firmness and a smooth surface.

More particularly, this invention relates to an improvement in the method of preparing aerated detergent bars invloving the extrusion of a continuous shape-stable strip of aerated detergent.

The preparation of detergent bars in a more or less continuous manner by agitating a partially solidified detergent mass within a critical temperature range and extruding the partially solidified mass is well known. Such a process, as applied to soap, is described in Mills, U.S. Letters Patent No. 2,295,594 granted September 15, 1942. The Mills process applies the principle that above room temperature, at which temperature soap masses of the type contemplated therein are in a solid state, certain temperature regions exist in which those masses While in a soft pasty condition can be extruded in a shape-stable continuous strip, i.e., the extruded strip retains its crosssectional shape and dimensions in a substantially unchanged condition until the extruded mass has cooled to a solid condition. The Mills process is effectively carried out by continuously introducing molten soap, along with any additives that may be desired, into one end of a scraped wall heat-exchanging and agitating device of the character disclosed, for example, in the patent to- Vogt, No. 1,783,864, granted December 2, 1930 and its Reissue No. 21,406, granted March 19, 1940, and which is also illustrated in the aforesaid Mills patent, wherein the soap is successively chilled while being subjected to intense agitation, passed through a mixing chamber and extruded from the other end of the said device through an orifice in a warm and pasty, but shape-retaining condition, as a continuous strip, cutting this continuous strip into segments, cooling these segments until they reach a solid condition, and then forming the segments into individual shaped tablets suitable for personal use.

The aforedescribed process is readily adaptable to the preparation of bars of many non-soap detergent formulations and formulations which include both non-soap detergents and soap and this is true whether the ultimate detergent bars are to be non-aerated, aerated or of the floating type.

in the formation of bars of soap or other detergents the problem of obtaining a smooth-surfaced product has always been paramount. With aerated products, and particularly with those products containing sufiicient vesiculated gas to make them float, this problem has been pronounced because of the tendency of the vesiculated gas to agglomerate or form relatively large vesicles or pockets of gas which tend to break through the surface of the bar during processing, thereby destroying its smooth and uninterrupted appearance. This problem has been especially present when detergent bars are produced by rapidly chilling a detergent formulation from the melt and then extruding it in a pasty but form-retaining condition. Traditionally, this problem was countered by making adjustments in the product formulation or processing conditions, usually to the detriment of other desirable qualities in the finished bar, such as firmness, or to the restriction of operation to within impractical limits. A drastic and impractically expensive expedient would be to shave off the rough bar surface.

Head, in US. Letters Patent No. 2,748,070, suggests a solution to the bar surface problem encountered in applying extruding apparatus similar to that employed by Mills, supra, through electrical lubrication of the extrusion orifice. Although this did present at least a partial solution to the problem, the relatively high cost of such apparatus, particularly if it is to be rendered free of shock hazard and safe in operation, militates against its use.

Another method for obtaining a smoother surface on the extruding detergent strip, and which is Widely used in the formation by extrusion of various plastic materials, is to heat the extrusion orifice plate, either by utilizing its electrical resistance or by other means. Here again, only a partial solution to the bar surface problem was obtained. Nevertheless, such a heated orifice plate is an excellent adjunct for use with the process of this invention.

A further object is to provide an improved method for preparing aerated detergent bars characterized by a smooth surface.

The preferred extrusion apparatus of the aforesaid Mills patent comprises in integral sequence, an inlet for the flowing detergent mass being processed, a scrapedwall heat exchanger, a mixing chamber and a discharge housing terminating in an extrusion orifice. The crux of this invention, by means of which the foregoing and other objects are accomplished, comprises the provision of an internal orifice-defining plate which is mounted between the aforesaid mixing chamber and the extrusion orifice of the extrusion apparatus transverse to the longitudinal axis of the apparatus and contiguous with the interior walls of the apparatus.

In the accompanying drawings:

FIGURE 1 is a longitudinal sectional view of a cooling and extrusion apparatus with which this invention finds application and depicts the interior orifice in appropriate position within the apparatus.

FIGURE 2 is a cross section taken along the line 2-2 of FIGURE 1 and shows the preferred embodiment of the interior orifice-defining plate of this invention.

FIGURES 3, 4, 5 and 6 depict modified configurations and arrangements of orifices within the purview of this invention although the invention is not to be construed as limited thereto.

FlGURE 7 is a longitudinal section of the extrusion end of a cooling and extrusion apparatus which depicts an alternative structure by which the objects of this invention can be accomplished.

Referring now to FIGURE 1, 10 denotes a conduit which functions as an inlet to annular chamber 11 which is defined by a generally cylindrical drum i3 and a shaft 14, the shaft being supported for rotation on the axis of the drum by conventional shaft supports (not shown). The drum 13 is formed of heat conducting material, such as metal, and is surrounded by a second cylindrical wall 15 to provide an annular space 16 having an inlet port 17 and an outlet 18 which functions as a cooling jacket. A plurality of scraper blades 19 are secured to shaft 14 at intervals about its circumference to bear against and scrape the inner surface of drum 13. A plurality of annular elements 2%, each of which is provided with a plurality of substantially radial inwardly directed arms 21, serving as bafiles are rigidly mounted within drum 22 which forms a continuation of drum 13. A shaft .23 is threaded or otherwise fastened to shaft 14 and forms a reduced extrusion thereof. Shaft 23 is provided with a plurality of substantially radial outwardly directed arms 24 which are disposed in proximity to the baffie arms 21 and cooperate therewith to function as an agitator or mixer. A tapered discharge housing 25 extends from the drum 22 and terminates in an exterior orifice plate 26 having an orifice 27. An interior orifice plate 28 having O a tapered flange I) is mounted within the in wedged relationship with respect to t e of tapered discharge housing 25.

Although in the foregoing description, as well as in FEGURE l, the orificodefining plate 28 is held in position in tle described apparatus by flan e 29, which is forced into wedged relationship with the interior wall of discharge housing 25 by the pressure of the detergent mass flowing through the apparatus from the inlet to the extrusion orifice, other means of holding the orifice-defining plate 28 in position will readily suggest themselves to those skilled in the art. For example, an orifice-defining plate devoid of fiange 29, but of sufiicient dimension to be contiguous with the interior walls of the extrusion apparatus, may be fastened within the apparatus by any suitable means to projections spaced about and radiating inwardly from the periphery of the interior wall of the extrusion apparatus within the preferred section hereinbefore indicated.

In the operation of the apparatus shown in FlGURE l the detergent mass to be processed, and which preferably contains a. compatible gas, is delivered under positive pressure through conduit 18 into annular chamber 11 while a cooling medium is being introduced to the annular space 16 through inlet port 17 and withdrawn through outlet 13. The detergent mass is forced to tlow through the chamber 11 in a relatively thin annular layer, the film of detergent which is chilled on the inner surface of the drum 13 being quickly scraped off by the scraper blades and mixed with uncooled detergent due to the agitation caused by the blades 19. A cooling medium consisting of water between about 35 F. and about 65 F. has been found satisfactory dependi. g upon the rate of water flow, the composition of the dot rgent mass being processed and the finished product properties desired. Other cooling media such as cold brine, liquid ammonia, etc., may, however, be used if desired. The detergent mass then passes through drum 22 where it is further mixed by rotating arms i i and by passing between stationary batlle arms 21 without additional chilling. It then passes into discharge housing where its flow is impeded by orifice-defining plate 23 and directed through the orifice in the said plate into the next consecutive section of the discharge housing from which it is extruded through orifice 27 as a form-retaining mass into the atmosphere; orifice 27 has the required shape to produce a continuous blank bar of desired form. This continuous bar is cut into individual bars of the desired length, and these bars are properly conditioned by a cooling treatment for the final stamping or pressing operation.

As an alternative to the use of an interior orifice-defining plate as hereinbefore described, an extrusion apparatus of the type shown in partial longitudinal scction in FIGURE 7 can be utilized in a complishing the objects of this invention. This figure shows, in longitudinal section, the extrusion end of the type of apparatus shown in FIGURE 1, the reference numerals common to both figures representing identical elements. In FIGURE 7, the constricted portion, 29, of discharge housing 30, functions to impede the fiow of the detergent mass being processed in an aquivalent manner to orifice-defining plate 28 of FIGURE 1.

The use of an interior orifice-defining plate 23. as heretofore described, gives rise to a number of wholly unexpected benefits, particularly when the ultimate cletergent product is to be a floating bar. For example, it aids in obtaining a product with a smooth surface. It also improves the heat transfer rate in the scrapedwall heat-exchanger section of the described apparatus. In addition, it promotes the formation of a firmer product, as opposed to when it is not used, and it improves the distribution of air or other compatible gas throughout the detergent mass.

The following considerations regarding the manner in which the foregoing benefits are achieved by the interior housing interior wall orifice of this invention are theoretical in nature and are not to be considered as limiting.

The production of an extruded aerated detergent bar characterized by a smooth surface appearance, particularly a bar which contains a sufficient amount of a compatible gas to make it float, is rather ditficult. Many factors have an influence upon the as extruded surface of the bar and a rather delicate balance of all these factors is required for a given detergent composition if the optimum in surface smoothness is to be attained. For example, with an aerated detergent bar there is a tendency for the gas dispersed in the detergent mass to be released from solution or to agglomerate into relatively large bubbles and break through the surface of the continuous detergent bar as it is extruded. The interior orifice of this invention functions to substantially decrease this source of trouble, all other factors being the same, by maintaining the detergent mass in the extrusion apparatus under a back-pressure which is greater than that which is normally encountered with such an apparatus having a given crosssectional extrusion orifice. This greater back-pressure suffices to keep more of the gas in solution in the detergent mass. As a result, when the pressure on the detergent mass is released, as upon extrusion through the orifice in the interior orifice-defining plate, dissolved gas comes out of solution in small bubble form, the bubbles being well dispersed throughout the detergent mass. It is also to be noted that in the apparatus described the interior orificedefining plate functions to release the pressure on the detergent mass in stepwise fashion thereby still further facilitating the distribution of the gas uniformly throughout the detergent mass in small bubble form. Thus, the detergent mass, which is under maximum pressure in the scraped Wall heat exchanger and mixing zone of the apparatus described, is released through the orifice in the interior orifice defining plate to a zone of lesser pressure defined by the said plate and by the final extrusion orifice plate whereupon some of the air or compatible gas is released in small bubble form in the detergent mass. From this zone of lesser pressure the mass is released to atmospheric pressure through the final extrusion orifice, whereupon some of the remainder of the gas in solution in the detergent mass is also released in small bubble form throughout the detergent mass. The dispersion of the compatible gas in such well-dispersed fine-bubble form, and which results from using the interior orifice of this invention, is a major factor in obtaining a smooth-surfaced detergent bar since there will be a greatly reduced tendency for the bubbles to break through and puck-mark the surface of the as extruded detergent strip.

A further, and also wholly unexpected benefit, derived from the operation of the interior orifice-defining plate to increase the back-pressure in the chilling and extrusion apparatus, is an improvement in the heat transfer rate in the scraped wall heat exchanger section of the apparatus. It is believed that this benefit flows from two facts:

(1) A greater than normal amount of the compatible gas is held in solution in the detergent mass. This reduces the possibility that the gas will form in bubbles or agglomerate in pockets on the interior wall of the chilling section of the described apparatus and interfere with the desired contact between this wall and the detergent mass being processed.

(2) The greater pressure more rapidly forces the detergent mass into intimate contact with the chilling wall of the heat exchanger after the scraper blades have removed the already chilled portion adhering to the wall.

A further benefit derived from the use of the interior orifice-defining plate is closely linked with extrusion temperature which, in turn, is influential in determining surface smoothness, again particularly with aerated detergent bars. In an apparatus of the type shown in FIGURE 1, but minus the interior orifice-defining plate 28, the detergent mass follows a laminar flow pattern in the discharge housing 25. Thus the material adjacent to the interior walls follows a path of flow along the walls and through the extrusion orifice, the flow through the orifice being in the outer periphery thereof to form, for the most part, the exterior portions of the extruded strip. The material in the central portion of the extrusion apparatus flows more or less axially in a straight-line path through the extrusion orifice and forms the interior core of the bar. With such action the as extruded bar is characterized by a temperature gradient over its cross-sectional area, the peripheral portions, which comprise the material flowing adjacent to the interior walls of the apparatus being cooler than the central core of the strip. This temperature differential was found to be a contributing factor to the difiiculties encountered in obtaining a firm and smooth-surfaced product upon extrusion.

With the present invention, the detergent material in laminar flow along the walls of the discharge housing is impeded in its flow by the orifice-defining plate and forced to pass through the orifice in this plate. As a result, this material is admixed with the axially flowing portion of the detergent mass being processed. -It is believed that further admixing is accomplished as the detergent mass flows through the subsequent section of the discharge housing and through the extrusion orifice. This intermixing which is induced by the interior orifice-defining plate tends to equalize the temperature throughout the extruding detergent strip so that over its cross-sectional area there is substantially no temperature differential. Because of this temperature equalization it has been found that the extrusion can be carried out at a somewhat higher temperature. This, in turn, promotes the formation of a firmer detergent bar at extrusion and also contributes to a smooth surface on the extruded detergent strip.

The present invention can be beneficially used to process any detergent mass, whether aerated or non-aerated and whether the ultimate product is to float or not, which when, subjected to the chilling and mechanical working accomplished in the type of chilling and extrusion apparatus described herein is converted to a state of pasty cohesiveness--that property of a detergent mass at the point of extrusion which enables freshly separated masses of the detergent to become reunited when brought together without requiring the application of high pressures such as those employed in plodding milled soap. Theorizing, the state of pasty cohesiveness may be considered as a thick pasty magma consisting of a mixture of solid crystals in a viscous matrix of unsolidified detergent-and this condition may, in fact, exist with some detergent compositions (see Mills, U.S. Letters Patent 2,295,594 granted September 15, 1942). Or, it may be considered to be a colloidal dispersion or emulsion of one detergent phase (e.g., neat, lye, nigre phases) in another. In any case, the detergent mass, in being subjected to the chilling and mechanical working in the extrusion apparatus, is converted to a state where its extrusion in a form-retaining continuous strip is possible.

It is to be understood that the term detergent as used herein is intended to include within its scope true soaps (e.g., the alkali metal salts of higher molecular weight fatty acids), synthetic detergents (e.g., anionic detergents such as sulfate or sulfonate derivatives of organic compounds that contain in their molecular structure an alkyl group having from 8 to 18 carbon atoms; nonionics, such as the Pluronics which are fully described in US. Patent No. 2,674,619 to L. G. Dundsted, granted April 6, 1954) and combinations of soaps and synthetic detergents. Also, it is contemplated that numerous organic and inorganic building and improving agents may be used in conjunction with the detergents referred to above.

This invention has been found particularly applicable and beneficial in the processing of an aerated detergent mixture comprising essentially a water-soluble alkali metal soap and an alkyl glyceryl ether sulfonatc, wherein the alkyl group is derived from the fatty acids obtained from coconut oil, in a ratio of about 2 parts soap to 1 part of alkyl glyceryl ether sulfonate, to form a floating bar. With this material, it was found that an extrusion apparatus of the type previously described, having a scrapedwall heat exchanger section six inches in internal diameter and eighteen inches long, with a free space for the detergent about one inch in thickness, with a shaft rotating at about r.p.m., with the jacket supplied with an adequate amount of brine at about 20 F. and with an interior orifice plate having a centrally located circular orifice three-eighths inch in diameter and sufiicient to maintain a back-pressure of about 60-80 p.s.i. in the scraped-wall heat exchanger and mixer sections of the extrusion apparatus, will satisfactorily process about 300 to 400 pounds of the aforesaid detergent mixture per hour. During processing, the temperature of the flowing detergent mass at the detergent inlet of the apparatus was about 180 F. and the temperature of the extruding shapestable continuous strip of detergent, the cross-sectional dimensions of which were approximately 2 /4 inches by 1% inches, was about F. The extruded detergent strip 'was firm and smooth-surfaced and was characterized by good air dispersion in small bubble form throughout its mass.

As has been pointed out hereinbefore, there are various other factors in addition to the back pressure in the extrusion apparatus which aifect the physical characteristics of an extruded detergent strip. A major factor is, of course, the detergent composition being processed. For purposes of this application, therefore, it is to be assumed that because of the wide variation which can be encountered in processing conditions such as extrusion temperature, rate of chilling, etc., no attempt is made herein to define such limits. Also, the desired degree of aeration of an extruded detergent strip and the tolerable imperfections in the strip surface may comprise additional variable factors. Further, conditions may vary depending upon whether an erated or non-aerated final product is to be produced and whether suificient air is to be incorporated to make the final product float. With the aerated prodnot it has been found that the lower limit of the back pressure, as determined by the size of the orifice to be used in the interior orifice-defining plate, is best established by determining the pressure at which air is soluble in the particular detergent material being processed. The upper pressure limit in all cases is limited only by equipment design but is, of course, affected by practical con siderations such as throughput rate. 1

Although with the soap-alkyl glyceryl ether sulfonate detergent mixture referred to above it has been found that a singular circular orifice located in the orifice-defining plate on the longitudinal center line of the chilling and extrusion apparatus is preferred, other typesof orifices, as shown in FIGURES 3, 4, 5 and 6 in the accompanying drawings are usable. However, it is not the intention herein to be limited by any of the accompanying drawings and in some cases even a wire mesh can be utilized to advantage.

In relation to the final extrusion orifice and the mixing section of the apparatus, the orifice-defining plate should not be closer to the final extrusion orifice than one effective diameter of the orifice which it defines when the orifice area is expressed in terms of an equivalent circular cross-sectional area, and it is preferably mounted as close to the mixing section as possible. In any event, the orificedefining plate should be mounted so that there is substantially no temperature differential over the cross-sectional area of the extruding detergent strip, and so that it defines, within the apparatus, a zone of higher pressure and a zone of lower pressure enabling a step-wise reduction in the pressure to which the detergent mass is subjected during processing to take place.

It is to be understood that, if desired, more than one interior orifice-defining plate can be used in the aforedescribed apparatus. For example, with the use of a plurality of such plates in sequence, a series of zones can apparatus between the mixing section and the extrusion orifice. These plates, and the orifices which they define, can be so positioned that each successive zone closer to the extrusion orifice the back pressure is lower than in the immediately preceding zone. Such arrangement provides a smaller incremental reduction in pressure from zone to zone than is obtained when a single interior orifice dcfining plate is used and thereby allows incremental portions of the compatible gas in solution in the detergent mass to be released from solution in the mass in small bubble form with the successive incremental pressure reduction from zone to successive zone. Incidental to the advantages coupled with the incremental clease of the air from solution in the detergent mass, accomplished through the use of such an orifice plate arrangement, and also depending in part upon the configuration and location of orifices in the plurality of orificedefining plates, additional mixing of the detergent mass is accomplished.

Although the present invention is of major importance in obtaining an aerated detergent composition of the type described which is characterized by a smooth surface, additional steps can be taken to still further improve the bar surface appearance. This can be accomplished by utilizing the invention of Head, US. 2,748,076, or the heated extrusion orifice plate, hereinbefore referred to, or if desired, by applying a jacket to the discharge housing of the chilling and extrusion apparatus through which a heating medium, such as hot water or heated oil, can be circulated.

Having thus described the invention what is claimed is:

1. in a process for preparing aerated detergent bars from a flowable detergent mass containing a compatible gas, by means of a device which extrudes the aerated detergent in a continuous shape-retaining strip and wherein the detergent mass moves sequentially in said device from the inlet thereof through a scraped-wall cooling zone, a mixing zone and discharge zone to an extrusion outlet, the improvement which comprises impeding the flow of the detergent mass beyond the aforesaid scrapcd-wall cooling zone and mixing zone and prior to the extrusion outlet whereby the said discharge zone is divided into a zone of higher back pressure and a zone of lower back pressure, the said mass in the zone of higher back pressure being under a pressure sufiicient to hold a major portion of the compatible gas in solution in the detergent mass, releasing the mass into the aforesaid zone of lower bacs; pressure, whereby a portion of the compatible gas in solution in the detergent mass is released from solution and becomes dispersed throughout the detergent mass in small bubble form, and releasing the mass through the extrusion outlet to atmospheric pressure, whereby compatible gas still in solution in the detergent mass is be defined in the 5.3 released from solution, the compatible gas being dispersed as vesiculated gas throughout the extruded detergent mass.

2. In a process for preparing aerated detergent bars from a fiowable detergent mass containing a compatible gas in solution, by means of a device which extrudes the aerated detergent in a continuous shape-retaining strip and wherein the detergent mass moves sequentially in said device from the inlet thereof through a scraped-wall cooling zone, a mixing zone and a discharge zone to an extrusion outlet, the improvement which comprises (1) impeding the flow of the detergent mass beyond the aforesaid scraped-wall cooling zone and mixing zone and prior to the extrusion outlet, whereby the said discharge zone is divided into incremental areas of pressure variation, the said mass in the zone of highest pressure being under a pressure sufficient to hold a major portion of the compatible gas in solution in the detergent mass, and (2) incrementally moving said detergent mass from an area of higher pressure to an area of lower pressure whereby the compatible gas in solution in the detergent mass is released incrementally from solution in the mass in small bubble form coincident with each incremental reduction in pressure.

3. The process of claim 1 in which the step of impeding the fiow of the detergent mass beyond the scraped-wall cooling zone and mixing zone and prior to the extrusion outlet is effected by means of an orifice defining plate situated at a distance from the extrusion outlet more than one effective diameter of a circular orifice equivalent in area to the total orifice area defined by said plate.

4. The process of claim 2 in which the step (1) of impeding the flow of the detergent mass beyond the scraped- Wall cooling zone and mixing zone and prior to the extrusion outlet is effected by means of an orifice defining plate situated at a distance from the extrusion outlet more than one etlective diameter of a circular orifice equivalent in area to the total orifice area defined by said plate.

5. The process of claim 2 in which the impeding of the flow of the detergent mass in step (I) is effected at a plurality of points beyond the aforesaid scraped-wall cooling Zone and mixing zone and prior to the extrusion outlet, whereby the said discharge zone is divided into a plurality of incremental areas of pressure variation.

References Cited in the file of this patent UNITED STATES PATENTS 2,291,212 Clinefelter July 28, 1942 2,295,594 Mills c Sept. 15, 1942 2,496,625 Henning Feb. 7, 1950 2,713,188 Garvey July 19, 1955 FOREIGN PATENTS 504,933 Italy Dec. 14, 1954 

1. IN A PROCESS FOR PREPARING AERATED DETERGENT BARS FROM A FLOWABLE DETERGENT MASS CONTAINING A COMPATIBLE GAS, BY MEANS OF A DEVICE WHICH EXTRUDES THE AERATED DETERGENT IN A CONTINUOUS SHAPE-RETAINING STRIP AND WHEREIN THE DETERGENT MASS MOVES SEQUENTIALLY IN SAID DEVICE FROM THE INLET THEREOF THROUGH A SCRAPED-WALL COOLING ZONE, A MIXING ZONE AND DISCHARGE ZONE TO AN EXTRUSION OUTLET, THE IMPROVEMENT WHICH COMPRISES IMPEDING THE FLOW OF THE DETERGENT MASS BEYOND THE AFORESAID SCRAPED-WALL COOLING ZONE AND MIXING ZONE AND PRIOR TO THE EXTRUSION OUTLET WHEREBY THE SAID DISCHARGE ZONE IS DIVIDED INTO A ZONE OF HIKER BACK PRESSURE AND A ZONE OF LOWER BACK PRESSURE, THE SIAD MASS IN THE ZONE OF HIGHER BACK PRESSURE BEING UNDER A PRESSURE SUFFICIENT TO HOLD A MAJOR PORTION OF THE COMPATIBLE GAS IN SOLUTION IN THE DETERGENT MASS, RELEASING THE MASS INTO THE AFORESAID ZONE OF LOWER BACK PRESSURE, WHEREBY A PORTION OF THE COMPATIBLE GAS IN SOLUTION IN THE DETERGENT MASS IS RELEASED FROM SOLUTION AND BECOMES DISPERESED THROUGHOUT THE DETERGENT MASS IN SMALL BUBBLE FORM, AND RELEASING THE MASS THROUGH THE EXTRUSION OUTLET TO ATMOSPHERIC PRESSURE, WHEREBY COMPATIBLE GAS STILL IN SOLUTION IN THE DETERGENT MASS IS RELEASED FROM SOLUTION, THE COMPATIBLE GAS BEING DISPERSED AS VESICULATED GAS THROUGHOUT THE EXTRUDED DETERGENT MASS. 